Electrical apparatus



June 18, 1940. H. R. ARNOLD 2,205,236

ELECTRICAL APPARATUS Filed May 25, 1938 WITNESSES:

Patented June 18, 1940 UNITED STATES PATENT OFFICIE ELECTRICAL APPARATUSvania Application May 25, 1938, Serial No. 210,082

2 Claims.

This invention relates to electrical apparatus and particularly to theforms for winding the coils of electrical apparatus.

An object of this invention is the provision of an improved coil formfor electrical apparatus.

Another object of this invention is to provide a form suitable forinsulating and supporting the turns of a coil.

A further object of this invention is the pro vision in coil form of aturn insulator of spiral form which will permit movement of the spiralturns relative to one another for accommodating the turns of a winding.

A more specific object of this invention is the provision in a coil of atwo-piece coil form suitable for supporting and insulating the turns ofthe coil.

Other objects of this invention will become apparent from the followingdescription when taken in conjunction with the accompanying drawing, inwhich:

Figure 1 is an elevational View in section of the core and coil assemblyof a transformer embodying the teachings of this invention;

Fig. 2 is an elevational view partly in section of a cylindrical body ofinsulating material comprising a portion of the coil form;

Fig. 3 is a View similar to Fig. 2 of a cylindrical body of insulatingmaterial embodying a modification of this invention;

Fig. 4 is an end view of a base or supporting member of insulatingmaterial; and

Fig. 5 is an elevational view partly in section of the base orsupporting member shown in Fig. 4.

Referring to the drawing, and particularly Fig. 1, this invention isillustrated as embodied in the core and coil assembly ll] of atransformer. The assembly illustrated in Fig. 1 comprises a laminatedcore member [2 which may be constructed in any suitable manner, and aprimary coil l4 and a secondary coil l6 disposed about the legs of thecore member 12. In order to prevent movement of the coils about the legsof the core member, suitable wedges ii are disposed between the coilform described hereinafter and the legs of the core member.

In constructing the coils M and Hi, the turns of wire are wound on acoil form [8 particularly adapted for supporting the turns and foradjustment or movement whereby it can be employed with difierent sizedturns of wire. In making the coil, a coil form l8 which comprises a coreor supporting member 20 of insulating material illustrated in Figs. 4and 5, and a cylindrical tubular member 22 of insulating material asillustrated in Figs. 2 and 3, is employed for sup porting and insulatingthe turns of the coil.

The core or supporting member 20 of the coil form is preferably a hollowbase of a fibrous ma- 5 terial impregnated with a synthetic resin, suchphenolic, urea or thiourea resin, molded under heat and pressure to thedesired form. In this form, the hollow base 2!) has an opening 24therethrough of any desired shape suitable 3 for receiving the legs ofthe core member i2.

In making the turn insulator 22 sheets of cloth, paper or the like,impregnated with a synthetic resin rolled into the form of a hollowlaminated tubular body which is molded under heat in and pressure to adesired form. As molded, the tubular body has an inside diameter equalto the outside diameter of the supporting member 2a, and a total wallthickness depending upon the turns to be applied to the coil, as will beexfro plained more fully hereinafter.

As illustrated in Fig. 2, the wall of the turn insulator 22 is so cut asto provide a continuous spiral groove or space 25, greatly exaggeratedin the drawing, from end to end of the member. This spiral groove orspace may be of a very fine cut with the turns so spaced apart as toprovide a thickness of insulating material between the turns suflicientfor insulating the turns of wire which are to be wound therein.

With the turn insulator spirally cut in the manner described, it isdisposed on the base member it for the winding of the coil. In formingthe complete coil, end collars 28 of suitable insulating material aredisposed about the ends 5 of the base member as illustrated in Fig. 1and extend outwardly to the outer edge of the coil. The base member 2dcarrying the turn insulator and end collars is then placed on a suitablemandrel and a turn of the winding is wound on the base member adjacentone of the end collars. As the first turn of the winding is completed,the end of the spirally cut turn insulator is placed between the firstand second turns of the winding and the winding proceeds with the spiralturns of the turn insulator separating the adjacent turns of thewinding. As illustrated in Fig. l, the turn of the winding is broughtout through suitable slots in the end collars 28 for forming the leads30 of the coil. The turn may or may not comprise a plurality of strandsof wire, one turn per layer being disposed between turns of the turninsulator.

Since the turn insulator is of tubular shape, it will have no tendencyto move radially from the base member and the turns of the winding willsecurely hold it in place longitudinally. Because of the inherent springaction of the spirally out turn insulator, it is evident that the turnsof the turn insulator are movable relatively to one another toaccommodate the turns of the winding as they are wound in the groovesformed by the turn insulator and the base member. Because the turns ofthe turn insulator are capable of movement relative to one another, itis apparent that a coil form employing such a turn insulator may beadapted to the making of a coil employing any predetermined size ofwire. After the coil is wound, in order to eliminate the possibility ofthe end of the turn insulator from creeping out of place between theturns of the winding, the completed coil is usually taped with one ormore layers of suitable insulating tape 32 as illustrated in Fig. 1 tohold the turn insulator in position.

Where the coil form is to be employed in the making oi coils embodyingheavy turns of wire, it is sometimes found that the thickness of theinsulation required between the adjacent turns of the coil is so greatthat the fine cut groove of the cylindrical turn insulator of Fig. 2cannot be adjusted longitudinally sufficient to receive the heavy turns.Where such heavy insulation is required between the turns of the coil,the tubular turn insulator is grooved in the manner illustrated in Fig.3 of the drawing. Here the turn insulator is double cut to form thecontinuous spiral groove or space 26 therein, the convolutions of thespiral out being so spaced as to provide spiral turns of the insulatorof predetermined thickness for giving a predetermined value of turninsulation. In this form, by reason of the double cut employed in makingthe groove or space, it is found that there is sufficient longitudinalflexibility as to permit a slight movement of the turns of the turninsulator relative to each other for accommodating different sized heavywire.

In practicing this invention, the thickness of the wall of the tube 22for making the turn insulator will depend upon its use in the coil. Theturn insulator may be readily constructed having a thickness equal tothe total turn thick ness of the coil, or where desired, a plurality ofthe turn insulators may be employed. In the latter case, the turninsulator may be of a thickness equal to the thickness of one turn, andwhen assembled on the supporting member 20 with the turn wound therein,may be covered with a suitable solid insulating material such as a sheetof paper, or suitable spacing strips may be disposed thereabout and asecond turn insulator having an inside diameter equal to the outsidediameter of the first turn insulator may be mounted thereon. Additionalturn insulators may be mounted thereon with separating insulator sheetsor spacers therebetween as the coil is wound to form the complete coil.By employing the plurality of turn insulators in the manner described,it is possible to construct a coil employing different-sized turns ofwires for the different layers of the coil, as desired.

The coil form of this invention has the advantage that the proper turninsulation is provided for a predetermined size of wire, while thethickness oi the insulator between the turns is sufficient forsupporting them in position. Further, the turn insulators, whether thegrooves or spaces are formed therein by means of the fine cut or doublecut, as described, may be used interchangeably upon the coil supporthaving the outside diameter of predetermined size.

Although this invention has been described with reference to particularembodiment thereof, it is, of course not to be limited thereto exceptinsofar as is necessitated by the prior art and the scope of theappended claims.

I claim as my invention:

1.1 coil form for a winding comprising in combination, a base ofinsulating material, a spacer consisting of a continuous turn insulatoroi fibrous material impregnated with a synthetic resin disposed on thebase, the continuous turn insulator being of self-supported spiral shapehaving a spiral space between the spiral turns of the insulator forreceiving the winding, the turns of the spacer being movable relative toone another on the base to adjust the size of the space for receivingdifferent sized windings.

2. A coil form for a winding comprising in combination, a base ofinsulating material, a spacer consisting of a continuous turn insulatorof fibrous material impregnated with a synthetic resin disposed on thebase, the continuous turn insulator being of self-supported spiral shapehaving a spiral space between the spiral turns of the insulator forreceiving the winding, the turns of the spacer being disposed edgewiseto the base and having a thickness sufficient to support the winding,the turns of the spacer also being movable relative to one another onthe base to adjust the size of the space for receiving different sizedwindings.

HEWETT R. ARNOLD.

